Air Navigation Conference 95
Boeing Perspective on FANS
David Allen
Abstract
Boeing took a proactive role in the development of the
ARINC 622 FANS 1 package because a business case analysis
indicated that it was of significant value to the airlines.
Boeing also determined that airframe manufacturer
involvement would add value to the development process, due
to the level of integration (both internal and external to
the airplane). There are several development and
certification issues which should be considered when
developing an integrated FANS package regardless of
protocol or functional allocation. The resolution of these
issues during the FANS 1 implementation can be used by
future developments to reduce risk. Currently Boeing has
developed and certified ARINC 622 FANS 1 for the 747-400.
The 777 will have ARINC 622 FANS 1 implemented as part of
the Market B package (retrofitable to Market A). Boeing is
presently evaluating the direction of CNS/ATM relative to
its 757/767 implementation. There is a need for an
economic analysis of North Atlantic operation to help drive
that decision process. The 737 currently has GPS, Company
Data Link, and Required Time of Arrival functionality
available. The Air Traffic Services implementations will
be added when required by the market place.
Why Did Boeing Develop FANS 1
All airplanes operate as a part of a larger Air Traffic Management
(ATM) System. Air Traffic Management refers to the integration of
ground based (airline/ATC) systems and airborne systems which control
movement and spacing of airplanes. The airframe manufacturer has the
responsibility to integrate their aircraft systems (automated,
procedural, training, and operational) with that larger environment.
However, this should not be considered a carte blanche rationale to
plunge headlong into system development; especially in todays business
environment.
Airline profitability is one of the keys to any airframe manufacturers
success. In 1993, Boeing was approached by four 747-400 operators who
saw a real value for ARINC 622 based FANS (Future Air Navigation
System) applications in the Pacific and Asia/Europe route structure.
Due to lack of airline interest, Boeing had previously suspended the
Package B upgrade which initially contained an ATN (Aeronautical
Telecommunications Network) based FANS package. By working closely
with the regional authorities, these airlines had obtained agreements
for implementation of benefits for airplanes which hosted FANS
applications and used the existing ACARS network. The benefit schedule
was agressive, but was supported by the regional authorities. The
implementation dates for ATN were supported by a committed plan and the
airlines felt that there would be a substantial delay in operational
cost savings if they waited.
Boeing led an effort to develop an economic model to quantify the
benefit/cost relationship for all interested parties: airlines,
avionics suppliers, ATC service providers, network service providers,
and Boeing. This model made it clear that all parties would win in
this endeavor; especially the airlines. This business case was
enhanced by the relatively low cost of the systems upgrades (because of
the use of existing systems and infrastructure) compared to the
potential savings of the 747-400 on those routes. So, the FANS 1
implementation made economic sense. The next question was the level of
Boeing involvement. Initially, the airlines had considered performing
the systems integration function. After reviewing the significant
airplane integration impact, they requested that Boeing take on the
system integrator role. The airlines remained intimately involved in
the development; especially in the design tradeoffs which are necessary
during every system implementation.
Boeing, therefore, took a proactive role in the development of 747-400
FANS 1 in partnership with the airlines because there was a clear
economic benefit to the airlines and Boeing participation as the
systems integrator added value to the process. This will be considered
the yardstick for any future development.
747-400 FANS 1 Development Issues
The implementation of ARINC 622 FANS 1 did not involve the introduction
of new technology. This was consistent with the ground rule which
required maximum utilization of existing equipment and infrastructure.
There were few development issues relative to the technology of FANS 1;
most issues were related to systems integration, both airborne and
air/ground.
There have always been integration requirements between Air Traffic
Control and aircraft systems. These systems were loosely coupled and
primarily mediated by the flight crew. The implementation of FANS 1
into a two-crew cockpit imposed greater integration requirements
between ATC and airborne systems. These requirements centered around:
Safety Analysis
Functional Allocation
Interoperability
Cockpit Integration
Operational Specification Approval
The Safety Analysis process is used to identify the potential hazards
of a function, classify those hazards, and allocate responsibility to
member systems. This is done early in the design process to assure
that all member systems reflect the appropriate criticality.
Criticality is comprised of availability criteria and impact of
hazardous behavior (versus planned operation). This process is
difficult enough when a complex airborne system is involved and the
function spans multiple systems. It becomes even more challenging when
the function extends beyond the domain of the aircraft itself. Figure
1 depicts the domain of the FANS 1 ATC Data Link (ATC D/L) and
Automatic Dependant Surveillance (ADS) functions.
<<snipped>>
Figure 1 - 747-400 FANS 1 ADS/ATC D/L Functional Domain
The ATC D/L function and ADS function were determined to be Essential
Level functions with regards to hazardous behavior but Non-Essential
with regards to availability. This means that the functions could be
lost; but must not provide misleading data to the flight crew. This
Safety Analysis was predicated on assumptions relative to the ATC
environment (both operation and integrity). The certification
requirements for 747-400 FANS 1 included FAA Notice 8110.50 which
required documentation of those assumptions. These were contained in
D240U123, Air Traffic Services Systems Requirements and Objectives
document (ATS SR&O).
This safety analysis drove both the functional allocation and design of
FANS 1. The tight coupling between the Flight Management function and
the ADS and ATC D/L led to the determination that the applications
should be hosted in the FMC. This coupling included both data
availability, flight plan state information, and report trigger
information. The criticality requirements for the functions removed
any remaining reservations. It was decided that the ACARS (Airline
Communications Addressing and Reporting System) and Satcom could
remain Non-Essential given a CRC (cyclic redundancy check) and address
verification which was decoded within the FMC.
Interoperability was another ATM (Air Traffic Management) system
integration issue. There were industry standards available which were
used in the specification process, but these standards did not
completely cover all integration issues. Boeing initiated an
Interoperability Meeting which included airlines, ATC service
providers, network service providers, civil aviation administrations,
avionics suppliers, and airframe manufacturers. The additional
requirements needed for interoperability were documented in the ATS
SR&O. Issues which were decided in this forum included:
ADS Emergency Mode Operations
Addition of time stamp to ATC DL messages for use in message aging
Changes to DO219 message set to support off-path operations
(Not covered in standard message set)
Definition of aircraft equivalents for altitude, fuel etc.
Consistent source of data required)
Handling and annunciation of data link system failures for
development of operational procedures
It is not the intent of this paper to recreate the ATS SR&O, but to
indicate that these issues do exist and need to be reconciled in any
FANS development.
The 747-400 was designed as a two-crew cockpit. It was crucial that
the addition of a function (such as ATC D/L) into this environment be
consistent with the flight crew operational procedures in order to
protect the two-crew operation basis. This meant that alerting had to
be considered as part of the overall crew alerting and warning system
and new operational procedures had to be integrated with the existing
procedures. This included new visual alerts pertaining to data link
availability in flight, data link equipment failure, data link status
for dispatch, and a series of messages required for GPS Required
Navigational Performance (RNP) capability (including aural alerts).
For ATC D/L down link messages, data is automatically provided to avoid
crew data entry where possible. For ATC D/L uplink messages, some data
(such as route information) can be automatically loaded into the Flight
Management System; again to avoid crew entry where possible.
New functions in the aircraft do not add value unless the airlines can
obtain Operational Specification approval via Part 121, to gain
operational benefits. Because of the close coupling of the airborne
and ground Air Traffic Management functions, sometimes the existing
documentation which is generally provided to an airline is not
sufficient. Boeing developed two new documents to support Operational
Specification approval. One was the ATS SR&O which has been previously
discussed. The other document was D240U126 Rev A, RNP Capability of
FANS 1 FMCS Equipped 747-400. The latter document (known as the RNP
document) gives the airlines data to provide to their Part 121
regulators to support GPS/RNP enroute, terminal, and approach
operations. This data, which is not part of the Approved Flight Manual
(AFM) or Operations Manual in that it provides analysis and data rather
than procedures, was used in the generation of the AFM and Ops Manual.
Certification of FANS 1 Functions on Boeing Airplanes
The 747-400 FANS 1 upgrade has been certified for all engine variants.
The initial certification for Rolls Royce powered airplanes was on June
20, 1995 (on a QANTAS airplane), the second certification for Pratt and
Whitney powered airplanes was performed on July 19 , 1995 (on a United
Airlines airplane), and the GE powered airplanes were certified on
August 2, 1995 (on an Air New Zealand airplane). There are now 14
operators which have purchased approximately 170 shipsets of the FANS 1
package.
The 737-300/400/500 airplanes currently have the option for
installation of RNP based GPS, Company data link, and RTA. The
implementation of FANS 1 ATC D/L and ADS functions are awaiting a
market-driven initiation.
The 777 Market A airplane was delivered with interim guidelines GPS
(not RNP) and Company data link. The Market B upgrade (which is
retrofitable to Market A) will provide full RNP based GPS, ATC D/L,
ADS, and RTA. This is scheduled for the fourth quarter of 1996.
What's Next - CNS/ATM wise
Potential CNS/ATM driven system upgrades are:
FANS for the 757/767
Multi Mode Receiver
Classics
Free Flight
ATN
Again, some airlines have approached Boeing with a request to
participate in a FANS implementation for the 757/767. Boeing has
hosted one meeting and will have another for 757/767 operators on
October 10-12, 1995. The initial meeting was with a group of airlines
currently specifying a particular architecture based on Buyer Furnished
Equipment (BFE). Other operators have asked for a 747-400 FMC based
FANS 1 solution. In either case, this will require the development of
a new FMC platform to host the FANS applications or the interface to
the new equipment, as well as have the capacity to incorporate ATN.
Boeing is currently studying the options and working with the industry,
will make a decision sometime after the October airline meeting. The
resulting proposal will be presented to a third airline meeting to be
hosted, by Boeing, before the year is out.
Boeing is also in the process of developing a plan for a potential
Multi Mode Receiver (MMR) based on industry interest. Its development
will be paced by the industry progress on defining the characteristics.
It is anticipated that the MMR will be accomplished in stages.
ILS "lookalike" MMR Installation
Development of MLS/MMR provisions
ILS/MLS MMR Installation
Development of GLS provisions
ILS/MLS/GLS MMR Installation
The goal is to have a definative plan in place to support the industry
decision relative to landing systems.
Another activity at Boeing is to evaluate our role relative to the
incorporation of FANS functions into the classic fleet (primarily the
747 Classics). Again, this evaluation will be using the FANS 1 747-400
business case analysis methodology. This evaluation has just begun and
no conclusions are available at this time.
Free Flight is the responsibility of the RTCA Task Force. It is too
early in the Free Flight task for Boeing to draw any conclusions as to
the impact on the airborn systems. The short term Free Flight
initiatives seem to be directed towards procedural improvements to the
Air Traffic System. The longer range plan involves Air Traffic System
changes (airborne and grounded) which will remove more of the
procedural restraints. Boeing has members on that Task Force and they
will be continually evaluating the results of the study with regards to
current and future Boeing products.
ATN Systems Incorporated has become the focal point for ATN
development. The Boeing Company will be represented in this industry
forum; but our final role has not been determined. The issue is not so
clear as with the 747-400 FANS 1 development effort. The ATN activity
also affects strategy relative to the 757/767. What is missing is the
overall business case for ATN based FANS applications. The initial use
of ATN will probably be in the North Atlantic, where 60% of the
crossings are made by twin engine airplanes. It would seem that the
basis for ATN equippage development would begin in this region.
However, the following is unknown:
Cost of ATN based airborne equipment
Timing of ground router availability
Definition of airline benefits
Scheduling of airline benefits
Scheduling of ground infrastructure development
Status on Procedure development
Boeing proposes that NATSPG become a forum for the development of an
ATN based FANS application business case using a decision based,
economic model. Boeing will provide the tool and the expertise for
developing this model and the NATSPG attendees will be responsible for
providing data. This economic (decision analysis) model provides Net
Present Value for the item being modeled. Ranges of values (such as
benefits, costs, and timing) can be used for the input (to indicate
uncertainty) and the model will use those to determine which entities
have the most effect on profitability. The model also creates a
spreadsheet output which will be distributed to NATSPG data providers
so they can take it home and add proprietary data. We have found this
model to be extremely useful in determining if benefits outweight cost
and the effect of variables (such as scheduling of benefits) on the
economic outcome. This is more complex than the usual cost/benefit
analysis because it allows the more precise representation of the
values and inter-relationships between equipage, procedures
development, and timed release of benefits.
This model can be used to help remove some and bound other
uncertainties associated with the development of the ATN. This model
could be used to support the business case for ATN implementation on
the ground or in the airborne systems by minimizing the uncertainty
associated with the economic analysis.
David Allen
FMCDave@AOL.COM
Project Manager, CNS/ATM
Opinions are mine and not Boeing's